We will cover …

(c) Nizar Mabroukeh 2001 1

We will cover… What is XML? Components of an XML Document Document Type Definition (DTD) XML Data Islands Parsing XML and DOM XML presentation with CSS, XSL and XSLT XPath, XML and Database Integration Why use XML? Creating your own XML vocabulary Review of XML Applications and Tools XML Resources

What is XML?


Markup Languages SGML:

Standard Generalized Markup Language Mother of Markup Languages

HTML Most popular presentation language for web

XML: Draws heavily on the merits & shortcomings of

HTML & SGML


Issues with HTMLMerits:

Very easy to use & learn Presentation technology It is the most popular

Shortcomings: NOT a data technology Poor Searching There is no Intelligence of content/data We loose meaning association with content Data cannot be represented hierarchically Limited set of tags


How does XML look? Simple XML data would look like

<book>

<title> XML Tech </title>

<author> YAG </author>

<level> Freshman </level>

</book>

<book> : Called the root node


XML HTML

Similar in appearance Both are based on SGML

BUT… XML describes data HTML displays data

XML

(eXtensible Markup Language)


What Is XML? “XML is a

platform-independent, self-describing, expandable, standard data exchange format that can be used either independently

or embedded and used within other

solutions.”


Platform Independent Windows Unix Macintosh Mainframe


Self-Describing Example:

<DATE>July 26, 1998</DATE>

Describes the information, not the presentation. Format flexible.


Expandable = Extensible HTML has a fixed set of tags

<H1>, <B>, <PRE>

XML lets you have your own tags <dangerous-substance>,

<Shakespearean-character>, <cash-equivalent>


Standard W3C (World Wide Web Consortium)

www.w3c.org

XML 1.0 specification was issued as standards-based text format for interchange of data as of February 1998.

W3C XML Working Group designed XML as a simplified subset of SGML


Standard XML specification does not define

any particular tag names (like HTML), instead it defines general syntactic rules enabling developers to create their own domain-specific vocabularies of tags.


balance sheet

total-assets

asset (current)

amount (1998)

$41,000,000

<balance-sheet><total-assets><asset-type="current">

<amount-period="1998"><amount>$41,000,000

</amount></amount-period>

</asset-type></total-assets>

</balance-sheet>

Context Greater context to the information Tree structure is natural in XML


Freedom Extensible markup language

Customized tags

Tags give meaning to the content

Separates data from style


Why XML? Derived as a subset of SGML Allows you to define your own tags

XML: <author> YAG </author>HTML: <B> YAG </B>

Provides meaningful & readable data Meaning searches can be performed Much simpler than SGML

SGML spec = 300 pages, XML = 33 pages Purely a Data Technology Supports compound documents.


XML Advantages

Web based

Extensible

License-free

Platform independent

Single end-to-end IT solution for electronic information exchanges

XML Documents

Authoring XML


XML Elements An XML element is made up of a start tag, an

end tag, and data in between. The start and end tags describe the data within the tags, which is considered the value of the element.

For example, the following XML element is a <chairman> element with the value “Sadiq Sait"

<chairman>Sadiq Sait</chairman>

Elements can be empty, to represent an empty element: <chairman/>

<book> Codebook 6.0 </book>

Opening Tag

Content Closing Tag

Element


XML Attributes An element can optionally contain one or

more attributes. An attribute is a name-value pair separated by an equal sign (=).

Example: <CITY ZIP=“31261">Dhahran</CITY>

Here, ZIP=“31261" is an attribute of the <CITY> element. Attributes are used as meta information


XML is…

…Case-sensitive


Parts of an XML document

Version Declaration

Document Type Definition (DTD)

<root>

BODY

</root>


Version Declaration

<?xml version=“1.0” encoding=“UTF-8” standalone=“yes”?>

Encoding: Supports Unicode 8, Unicode 16 & Others In short: Provides for multi-lingual data

Standalone: Indicates whether the document has any

markup declarations that are external to the document


XML data This is how XML data would look like (the

body of the document):

<books><book>

<name> Codebook 6.0 </name> <author> YAG </author> <level> Intermediate & Advanced </level>

</book><book>

<name> Jave for Beginners </name> <author> Dale </author> <level> Beginner </level>

</book></books>


XML Document Rules ONE Root element

ALL tags start AND end

Tags cannot overlap and are case sensitive

Attribute values enclosed in quotes

Attributes not repeated in an element

FIRST item must be

<books>

<book></book>

<book ISBN=“21-458-65-0”>

<para id=“1” s:id=“4”>

<?xml version=“1.0”?>


Two types of XML documents

Well-formed XML documents

Valid XML documents


Well-formed document Must contain one or more elements Must contain a uniquely named root element All other elements within the root element must

be nested correctly An XML parser will reject malformed documents

(the method of rejection will vary by parser author)

Documents that contain XML and HTML tags are common

HTML within an XML document must be well-formed


Valid XML document The XML document must be well formed Should contain a Document Type Definition

DTD is a schema which contains the constraints for the XML document

It contains Element definitions and their Attributes

Attributes should comply with the following rules Cannot contain <, & or a single ‘ or ‘’.

Elements must be nested correctly


Document Type Definition DTD is a text document that defines

the lexicon of legal names for tags in a particular XML vocabulary

It also defines how tags should be nested

It can be written as code inside the XML file or specified externally as a separate text file with extension .dtd


Sample DTD

<!DOCTYPE book [

<!ELEMENT book(name,author,level)+>

<!ELEMENT name(#PCDATA)>

<!ELEMENT author(#PCDATA)>

<!ELEMTNT level(#PCDATA)>

<!ATTLIST author email CDATA #IMPLIED>

]>

DTD may be specified externally with .dtd extension <!DOCTYPE book SYSTEM “book.dtd”>


More on DTD Special software can help you build your

DTD document visually instead of having to write all this weird code, example software package is “XML Authority” from Extensibility

An XML document is associated with a corresponding DTD document for validation using the <!DOCTYPE…> tag


Why use a DTD? Application independent way of

sharing data Industries or trading parties can agree

on a standard for interchanging data Verification that data received from

trading parties is valid.


Complete XML document<?xml version=“1.0” ?>

<!DOCTYPE book [

<!ELEMENT book(name,author,level?)+>

<!ELEMENT name(#PCDATA)>

<!ELEMENT author(#PCDATA)>

<!ELEMTNT level(#PCDATA)>

]>

<book>

<name> Codebook 6.0 </name>


<level> Intermediate & Advanced </level>

</book>


OR

<?xml version=“1.0” ?>

<!DOCTYPE book SYSTEM “book.dtd”>

<book>

<name> Codebook 6.0 </name>


<level> Intermediate & Advanced </level>

</book>


XML Document Pluses Tightly Structured Extensible Easily models data Useful for applications and transfer

between applications Interchangeable

XML Data Islands

XML inside HTML


XML Data Islands A data island is an XML document that

exists within an HTML page. It allows you to script against the XML

document without having to load it through script or through the <OBJECT> tag.

Almost anything that can be in a well-formed XML document can be inside a data island


How to create XML data island

The XML for a data island in HTML can be either:

Inline using ID,

or called from an outside xml file using SRC,

or created using a <script> tag


Inline data island The <XML> element marks the beginning

of the data island, and its ID attribute provides a name that you can use to reference the data island.

<XML ID="XMLID"ID="XMLID"> <customer>

<name>Mark Hanson</name> <custID>81422</custID> </customer>

</XML>


XML referenced from outside file

referenced through a SRC attribute on the <XML> tag:

<XML ID="XMLID" SRC="customer.xml"SRC="customer.xml"></XML>


Created using <script> tag

<SCRIPT LANGUAGE="xml" ID="XMLID"LANGUAGE="xml" ID="XMLID"> <customer>

<name>Mark Hanson</name> <custID>81422</custID>

</customer> </SCRIPT >

Parsing XML


What is XML Parsing For a computer program to access the

structured information in the document in a meaningful way, parsing is required

The parser first reads the stream of characters and recognizes the syntactic details of elements, attributes and text in the document

Then, the parser exposes the hierarchical set of information in the document as a tree of related elements, attributes and text items


The logical tree of information items created after parsing the XML document, is called the Information Set or Infoset

This can then be manipulated in different ways and data extracted for usage in applications, databases,…etc


XML Parsers Always check for well-formedness Can be validating or non-validating Validation required association with DTD

document Included in Microsoft Internet Explorer 5.0 Language-neutral programming model By using W3C XML 1.0 and XML DOM it

supports JavaScript, VBScript, Java, C++, Perl


Manipulating XML using the DOM

W3C provides a standard API called the Document Object Model (DOM) to access an XML document’s infoset

The DOM API provides a complete set of operations to programmatically manipulate the node tree including navigating the nodes in the hierarchy, creating and appending new nodes, removing nodes, etc.


Once you are done with making changes to the node tree you can save it and serialize the infoset back into an XML document

xml infosetparsing

serialization


DOM Properties & Methods An XML document object is created when an XML

data island is loaded and parsed…. and it has Properties & Methods

XMLDocument: Returns a reference to the XML DOM exposed by the object

documentElement: Returns the root element

childNodes: Returns a node list containing children (if any)

item(id): Access individual nodes through an index (zero based)

text Returns the text content of the node

Let’s look at an example…


DOM Example<XML ID="xmlDocument"> <class> <student studentID="13429"> <name>Jane Smith</name> <GPA>3.8</GPA> </student> </class></XML>

All of the below begin with xmlDocument.documentElement.childNodes.item(0).childNodes.item(0).text Returns "James Smith".childNodes.item(1).text Returns "3.8".text Returns "James Smith 3.8" i.e. name & GPA

Note: Everything is case sensitive hereNote: Everything is case sensitive here

Data Island

XML Presentation

Viewing XML


Viewing XML Unlike HTML, XML does not predefine

display properties for specific elements.

C++ Data Source Object (DSO) Binds XML to HTML and gives better

performance, built in IE 5.0

Cascading Style Sheets (CSS)

Extended Stylesheet Language (XSL)


CSS Separate file with a .css extension

object,+ {[property name]:[property value] ; + }

DIV {color:red; font-size:16pt}

/* Comments are entered the C way here */


Displaying XML with CSS Modify the

presentation of XML Documents

Follow normal CSS syntax

Referenced in the XML source document

paragraph{ COLOR: red; FONT-FAMILY: 'Book Antiqua'; FONT-VARIANT: small-caps; FONT-WEIGHT: bolder}preamble{ COLOR: blue; FONT-FAMILY: 'Book Antiqua'; FONT-VARIANT: small-caps; FONT-WEIGHT: bolder}

<?xml-stylesheet type="text/css" href="const.css"?>


XSL eXtended Stylesheet Language

Syntax is similar to XML

In fact, XSL is written in XML


The aim of XSL is to provide a simple but powerful stylesheet syntax, which can be used to define how XML documents should appear on the screen.

An XSL stylesheet transforms an XML document into a suitable form for presentation

It allows us to control how and which parts of the documents should be shown to the user.


The XSL processor takes an XML document as input, and translates it into a different XML document suitable for output. This resultant XML document can be passed through a separate tool to add the finishing touches ready for presentation.


Displaying XML with XSL More powerful

than CSS XSL documents

are XML documents

<xsl:for-each select=“books/book" order-by=“author">

<TR VALIGN="top" > <TD>

<xsl:value-of select="name"/>

</TD><TD><xsl:value-of

select=“author"/></TD></TR>

</xsl:for-each>


XSL Styling Tools


XSL Style Sheet

DTD

XML Document

XM

L P

arse

r

XS

L P

roce

sso

r

Web Browser

Other(e.g. Directly into

Application

Integrated use of XML


XSLT

eXtended Stylesheet Language for Transformations

Transforms XML from one tree-based structure to another


Advantages of XSLT Convert between XML vocabularies

used by different applications

Present data from an XML document by transforming it into HTML, or another format that’s appropriate to the user or special device requesting the data

Database Integration

Query and Search XML documents


XPath

XML Path Language is a W3C standard

It is a declarative language

Used to interrogate an XML document to select subsets of information


XPath provides a method for addressing parts of an XML document.

Allows string, number and boolean manipulation Treats XML document as set of nodes, allows matching

It is called a Path language because it is design like the path notation in URLs and files in directories


XPath Example/MovieList/Movie/Cast/Actor/* returns all info about all actors

/MovieList/Movie/Cast/* returns all info about Cast including that of Director and Actor and

Actress

To find attributes instead of elements we use @

/MovieList/Movie/@Title returns titles of all movies

//Actress/@Role returns the Role of any Actresses anywhere in the document


Find the Cast of any movies directed byMinghella with a running time greater than130 minutes:

/MoiveList/Movie[Director/Last=‘Manghella’ and @RunningTime >130]/Cast


Where to Use XPath<Item Context="{Xpath here}" Type="">

<Label>Your Name</Label>

<Interface>

<EditableField Duid="{Xpath here}">

<Value>Tony</Value>

</EditableField> </Interface>

</Item>

Logical:

<TD NOWRAP="NOWRAP" ALIGN="LEFT">

<INPUT TYPE="text" SIZE="48" VALUE="Tony" Name="{Xpath here}"/>

</TD>

HTML:


Using XPath Create an XPath for each unit of

information Carry the XPaths with the information as

it is transformed into other formats Use XPaths to link language strings and

labels with the information they describe

Generate an XSL stylesheet that uses the XPaths to generate the outgoing message

You should be using XML

More reasons for you to use XML


Why should I use XML XML enables a data web of

information services; it is vendor-neutral, platform-neutral, language-neutral technology

Simplifies application integration, consider the following example


Simplifies Integration If a company has:

Machines running OS from Sun, HP, IBM… Databases from Oracle, IBM, Microsoft… Packaged applications from Oracle, SAP…

An XML-based representation of data and the HTTP protocol might be the only things these various systems can ever hope to have in common!

Especially if you want to integrate them over the Internet


Why should I use XML XML also simplifies Information

Publishing and ReuseWith XML and XSLT you can easily:

• Separate data from presentation, allowing you to change the look of information without affecting application code

• Publish the same data using output styles specific to each kind of requesting device: browser, cell phone, PDA or another computer, etc.


WML: Wireless Markup Language for cell phones and PDAs

SVG: Scalable Vector Graphics language for rendering rich, data-driven images

XSL Formatting Objects: for high-quality printed output

Creating your own XML Vocabulary


XML Vocabulary The set of XML elements and

attributes for a certain application is called an XML Vocabulary

Can be used in more than one XML document for the same application


Create your own… Begin each document with an XML

decleration<?xml version=“1.0”?> (case-sensitive)

Use only one top-level document element cannot be repeated

Match opening and closing tags properly (notice case-sensetivity)


Add comments between  characters

Start element and attribute names with a letter. Cannot contain spaces

Put attributes in the opening tag

Enclose attribute values in matching quotes


Use only simple text as attribute values

Use < and & instead of < and & for literal less-than and ampersand characters

Write empty elements as <ElementName/>

If you follow these rules then your document will be a well-formed XML document

Review of Applications and Tools


XML Tools Help author the grammars (Schema,

Filter, Updates)

View, Edit & Manage XML

Define mappings between XML logical views & Databases.


How is XML used? Publishing

Create once, use many Database Management

Database integration e-Business

Key driver


XML Creation Tools

Two schools:

Data centric

Document centric


Microsoft XML Notepad

Free Tree-

based Great

search

msdn.microsoft.com/xml/notepad


CueSoft eXML Tree or

source view

Attribute handling

No search No nav bar

in source view

www.cuesoft.com


Techno2000 Clip! Powerful Flexible Wizards DTD

creationhttp://www.t2000-usa.com/download/download_index.html


Vervet Logic XML Pro More

expensive

www.vervetlogic.com


Document Oriented Examples

SoftQuad XMetaL Corel WordPerfect 9 Arbortext Adept Editor

Not as good for data development Require DTD or equivalent


XSL Tester

Free Open

source VB

www.vbxml.com


XML Authority from Extensibility


XML Authority from Extensibility

DTDs

Schema


Other Choices Web-based

DTD Generator• www.pault.com/Xmltube/dtdgen.html

IBM Suite Visual DTD Visual XML Transformation


Utilities

File manipulation XML Junction

• www.xmljunction.com

ODBC2XML


Security

IBM’s XML Security Suite www.alphaworks.ibm.com/tech/

xmlsecuritysuite


Programming and XML

Programming tools and environments Java including JAXP Visual Basic (VB) and Visual

Basic for Applications (VBA) Databases and other tools

Document vs. event driven processing (DOM vs. SAX)

Resources for XML


Software Sources Interesting sites

www.xmlsoftware.com

alphaworks.ibm.com

www.garshol.priv.no/download/xmltools/std_ix.html


WebSites

The Mother Ship www.w3c.org/xml

Heavy Stuff www.ibm.com/developer/xml msdn.microsoft.com/xml www.oracle.com/xml/ java.sun.com/xml/


More Resources … XML Information sites

www.xmlinfo.com www.xml.com www.xml.org www.xmlelephant.com metalab.unc.edu/xml/ www.ucc.ie/xml/

XML Tutorials www.xml101.com


More Resources … XSL Information

http://www.mulberrytech.com/xsl/xsl-list

VB XML Information mailto:[email protected]


And finally…

We’re only at the very start of the Web revolution.

XML is the fundamental building block

XML technology is moving forward, and Standards are rapidly evolving


Thank You